Ponente
Descripción
Blazars are a sub-class of Active Galactic Nuclei (AGN) and constitute the most populous class of sources in the extragalactic very-high-energy (VHE) sky. They are characterized by stochastic variability that spans from radio to VHE gamma rays (E > 100 GeV), whose origins are still being debated. Detecting more VHE blazars at different energies and distances is crucial for a better understanding of their emission mechanisms.
The Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) is located on the Roque de los Muchachos in La Palma, Spain. Due to its large photon collection area, it is sensitive to energies down to tens of GeV, making it the best-suited instrument to observe gamma-ray sources such as distant AGN that are affected by the photon-photon interactions with the extragalactic background light (EBL). From 2020 to 2022, we accumulated more than 150 hours of data of several well-known AGN with redshifts in the range 0.03 to 0.45: Mrk 421, Mrk 501, 1ES 1959+650, 1ES 0647+250, PG 1553+113. We present here the results on the spectral variability from early observations of bright AGN with LST-1. We perform a time-resolved spectral analysis using a Bayesian block algorithm for the brightest sources. We present joint analyses of contemporaneous Fermi-LAT and LST-1 data, covering the energy range from 300 MeV to 10 TeV, demonstrating good overall agreement between the two instruments. We also evaluated the potential of the LST-1 to detect flares from AGN by simulations of historical flares.
